1. Field of the Invention
The present invention relates to an x-ray illumination device and method using synchrotron radiation or the like and also to an x-ray exposing device and device manufacturing method.
2. Description of the Related Art
FIG. 6 is a configuration diagram illustrating an example of known x-ray exposing devices used for manufacturing semiconductors. A sheet-like SR light 3 is expanded in the Y direction, so that the SR light is cast upon the entirety of the mask 12. The SR light is not converged with this mirror system, and the light is cast upon the mask without alteration.
Such systems are usually controlled so that the center of the intensity distribution of the SR light in the Y direction is not shifted only in the Y direction as to the reflective surface of the x-ray mirror 19. This is because the intensity of the x-ray cast upon the mask changes greatly due to Y-directional shift between the SR light and the reflective surface of the x-ray mirror.
Specifically, the Y-directional mirror driving means 16 is controlled by the control means 17 according to the output of the SR light position sensor 18 such that the center of the intensity distribution of the SR light in the Y direction is not relatively shifted from a certain position on the reflective surface of the x-ray mirror.
However, with the above known example, it is difficult to keep the relative positional shift between the x-ray and the reflective surface of the x-ray mirror within a certain range at all necessary frequencies, due to the reasons described below.
First, description shall now be made regarding the relation between the amount of shift between the x-ray and the reflective surface of the x-ray mirror, frequency, and fluctuation of intensity distribution.
The following can be listed as causes which generate relative positional shift between the x-ray and the x-ray mirror, thereby causing irregularities in the intensity distribution of the x-ray cast upon the mask.
(1) Change in the emission position or emission direction of the x-ray due to movement of the electron orbit of the SR. PA0 (2) Relative positional change between the light source and the x-ray mirror due to floor vibrations or vibrations in the x-ray illumination device or SR ring due to floor vibrations. PA0 (3) Deformation of the building (floor on which the device is installed) due to temperature changes.
It is understood that a combination of these factors causes relative vibration of the incident x-ray as to the reflecting surface of the x-ray mirror, thereby causing positional offset. The amount of intensity distribution fluctuation due to this positional shifting is determined by the amplitude (amount of positional shifting) thereof and by the vibration frequency. Of the vibration frequency components of the positional shifting, frequency components which are sufficiently high as to the exposure time for one exposure can be ignored, since the intensity distribution fluctuation thereof is averaged out by the vibration occurring multiple times during the exposure period.
On the other hand, regarding changes at frequencies lower than what can be ignored, positional control must be implemented so that the positional shift between the x-ray and the reflective surface of the x-ray mirror is kept within a certain value. Accordingly, the shorter the exposure time is, the higher the control frequency must be.
However, since x-ray mirrors are usually mounted in a super vacuum, a special mechanism is required, such as a driving mechanism capable of operating in such a super vacuum or a driving force from a drive source positioned in the ambient atmosphere by means of metal bellows or the like. In addition, x-ray mirrors tend to be large and heavy. Accordingly, a large-scale driving device is needed to move the mirror at high frequencies and great amplitudes. At even higher frequencies, the vibrations near the natural vibration of the mirror driving device or supporting system such as the frame induced resonance, which makes controlling difficult in some cases. In light of the above, there are limitations to the extent to which even higher precision can be pursued, in the event that only the known method of just controlling the position of the x-ray mirror is employed.
On the other hand, there is a method wherein the electron orbit of the SR is measured, thereby controlling the position of the electron orbit, i.e., the point of emission, according to the measured values, so as to restrict the positional shift between the x-ray and the x-ray mirror. However, the electron orbit is measured by measurement equipment fixed either to or near the SR ring, so this problem cannot be resolved with respect to floor vibrations or deformation of the building. Accordingly, positional control of the electron orbit must be carried out, and, at the same time, floor vibration for the SR ring must be dealt with. In order to deal with the low-frequency floor vibrations, a vibration-reducing mechanism must be provided to the SR ring. However, taking the weight and size of the SR ring into consideration, it is thought that providing a vibration-reducing mechanism for low frequencies to the SR ring is difficult. In addition, it is quite expensive to vibration-proof the entire building for a range that includes low-frequency vibrations. Even in the event that such a vibration-reducing mechanism happened to be installed, it would not be able to deal with extremely slow positional changes such as deformation of the building due to temperature changes.
Consequently, there is an upper limit to the frequencies for controlling the position or attitude of the x-ray mirror, and there is a lower limit to the frequencies wherein control can be executed since the effects of floor vibrations can be felt even if the electron orbit of the SR ring is controlled. Accordingly, it is difficult to restrict the intensity distribution fluctuations due to shift between the x-ray and the x-ray mirror using only one of these two types of control.